Lead-pencil mechanism



'C. HOF MANN LEAD PENCILMEGHANISM Filed August 17. 1922 Feb. 23 1926.

Wife/SS A piece. 26 vwhich is externally accessible and upon which the tipstructure l'may be detachably carried. In the particular constructionshown, `the cuff 25 litsneatly wit-ln in the thimble 22 and has its apertured, er inwardly-flanged, bottom engaged in the annular groove or recess between base-disc 20 and the bottom of the thimble 22, so that the ruff, together with its attached screw sleeve' is rotatable, but is anchored against axial displacement from the supporting barrel l0. 'lhe forward portion of this cuff provides. just beyond the forward Vend of the barrel l0 and thimble 22, `a knurled turning ring 26, exteriorly accessible, and the front end of this ring is reduced, neatly to receive the open rear end of the detachable tipshell.

The lead-propeller 18, completing the lead-propelling mechanism, is a cylindrical nutV to engage the screw threads ofv the screw-sleeve, and Vhaving a pair of arms 32 entering the side slots of the lead-guiding tube to carry, within the tube., the pushing` stem 33 that engages the inner end of the leadstick.

Manifestly, when this feeding mechanism is completelyassembled and mounted in the barrel, rotation of the screw sleeve by means of the turning' ring 26 will advance or retractthe nut 18 along the fixed lead-tube 16 which holds said nut against rotation and is itself guided and supported in the annular nut. The rather-fragile lead tube of course receives support also at its base end and it is preferably supported near its forward end in the end ring 17 of screw sleeve 17. In use, no part of the feeding mechanism need ever be removed, and thus liability to loss or injury kofparts is minimized.

The tip structure, which preferably is nir-deremovableV for convenience in reloading, is a tapering shell preferably thickened at its forward end to provide a cylindrical bearing 35 for the lead-stick, this thickened end being preferably slotted longitudinally as at 36 for a suflicient distance to make it yieldingly clamp upon the lead-stick to give a firm, non-waliibling writing-point.` At .its

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open rear end the tip-shell is shaped to slip fitover the reduced part of the turning-ring 2G, and adjacent said rear end there is secured in the tip-shell a tubular guide-structure 38 which may also serve to detachably connect the removable tip with lthe barrelcarried parts. Guide 38 is of suitable diamc'er neatly to receive the slender, stem-like portion of the feed mechanism which projects forwardly beyond the turning member, and preferably7 such guide extends along the screw-sleeve 1almost to theA base of the latter. Part 38 therefore acts as a guide in assembling the tip with the barrel-carried parts, as graphically shown in Fig. 3, and insures the straight alignment of parts, in placing the tip, which will prevent lead-breakage.

In the form shown, this tubular guide has at itsy outer end a cupped flange 39 which extends to and is secured in the tip-shell, and also said guide preferably has provision for making screw threaded engagement with the turning part 26, well within the barrelcarried structure. Specifically, the guide may be long enough to reach almost to the cupped head 24 of the screw stem 17. and between its ends at a point in rear of the open base of the tip-shell, it may be exteriorly threaded as at 40 for engagement with internal screw-threads 41 ycarried by the rotatable culi 25. For manufacturing purposes it is desirable to form the threads 4l on a cuff-,liner IQ that is securely fastened in the cuff.

It will be apparent that the tip structure mayjreadily be removed from the barrelcarried feed niechanism as shown in Fig. for reloading purposes, when, as I prefer, the slotted end of the tip snugly grips the lead-stick andthe lead tube rather-loosely engages such lead, the tip will carry the lead with it on removal, as shown in Fig. 3. On reassembly, even when the lead so .carried by the tip is long, the provision of the 'tubular guide insures that the rear of the lead will assuredly re-enter the lead-tube without breakage. When one lead eX- hausted, the propeller nut 18 should be backed to the bottom end of its screw sleeve 17, the tip removed, the new lead inserted in the lead tube 16, to project somewhat beyond its forward end, and thetip replaced. Of course when the tip is replaced on the feed assembly, the stub of used lead is driven out by the end of the new lead.

It will be observed that by the structure described I provide a feed mechanism ade ouate toA handle a lead of considerable length. in a structure so compact longitudinally that the portion enteringthe barrel Y1.0 may be Vshort approximately only 'the amount suliicient for strength ofy union between the barrel and pencil mechanism. Also it will be noted that many advantages are attained by refinements shown. The pencil mechanism is especially rugged, de-

spite the desirably-light, thin-metal character of its parts, and presents always a firm. steady writing point. The tip structure. it will be seen, will never get loose or laterallywabbly, because the fitting of the broad base of the tip-shell on the turning-ring in one plane and the threaded engagement of' the tubular guide with the rotatable cuff-liner at a point well in rear of that plane gives a particularly strong, desirable joint.

lVhile I have herein described in considerable detail a specific construction having advantageous details particularly adapting i, for quantity 'production at minimum assembly-cost, and some details of which structure I may claim, it will be apparent lllf) ing said tube to act againstthe lead and havine' a Jortion outside of sai-d tube ada tp i ed to engage a screw member to be propelled thereby, a screw member surrounding said tube and engaging said propeller element, said screw member having its inner end connected with said barrel to hold it against longitudinal displacement but free for rotation with respect to said barrel and to said lead-tube, and having connected for rotation with said rotatable element a turning member which is exteriorly accessible to the fingers and arranged beyond the forward end of the barrel, and a tip structure extending from said turning member to a point. beyond the end of the lead-tube',-and being free fromthe latter and demountably attached to the barrel-carried structure. i Y 2.- In a pencil mechanism of the character described, the combination with a barrel, of a centrallead tube adapted and arranged to receive'the entirey rear portion of a lead structure and rigidly connected with said barrel, a propeller element having a portion entering said tube and a portion outside of said tube adapted to engage a screw member to be propelled thereby, a rotatableV screw member surrounding said tube and at its rear end entering within said barrel and there secured against longitudinal displacemont relative to said tube or the barrel, and

a tip-structure surrounding the forward portion of-said screw member and lead-tube and at its rear end detachably connected with the rotatable screw member.

3. A structure set forth in claim 2 wherein said rotatable screw member has a turning member beyond the end of the barrel and exteriorly accessible and said tip-member has a rearwardly extending part entering within said turning member for detachable connection with said rotatable screw member.

4. In a pencil mechanism of thecharacter described, theY combination with a barrel open at its end, vof a thiinble shallowly seated in said barrel and fixed therein, a fixed, slotted lead tube carried by said thimble. a .rotatable screw sleeve surrounding said lead tube and retained against longitudinal movement in, or removal from, the

barrel. said tube having a turning-portion accessible beyond the end ofthe barrel, and a propeller member havinga portion surroundingnsaid lead-tube and engagingsaid screw sleeve and a portion entering the lead tube to engage a lead stick therein.'-

5. In a pencill ofl the character described, 'Y

the combination withabarrel open at its end, of a central slotted lead tube to receive and frictionally hold the lead, said tube shallowly entering'I and secured in the4 open end 'of said barrel, a rotatable screw sleeve surrounding lsaid lead tube and securedv against axial displacement from said barrel, a propeller element engaging the thread ofthe screwsleeve and entering the lead guiding tube, and a tip structure, having a lead guiding orifice at its forward end, detachably mounted .on said screw sleeve structure.: Y y

' 6. yIn a pencil of the character described, the combinationof a barrel, a feed structure `permanently connectedl with, said barrel, comprising a fixed lead tube adapted to receive and frictionally hold the lead and Y having 'a slot, a propeller member entering said slotted tube, a feed screwinember surrounding and rotatable `about the ltube and engaging said propeller member to feedfit, and a tip structure detachably engaging the feed screw structure, whereby the tip may be removed without displacement of' any lead-feeding part@ 7. A structure as set forth in claim 6,' whereinsaid feed-screw structure has an externally accessible turning vmember of greater Adiameter than the tube and said tip structure engages said turningl member, combined with a tip-carried guide arranged near its rear end to receiveAV and `guide the screw member. i

8. In a pencil of the character described, i

the combination ofa barrel, feed-mechanism carried by the barrel and presenting a slen- .l A der stem-portion of the feed rmechanism v protruding beyond the end ofthe barrel, a

tip-structure detachably connectible with the barrel-carried mechanismto encompassy said slender stem-portion and extend taperingly theiebeyond,ftlie forward end of the tip eing constructed for engagement witha lead stick to carry the lead stick with it on removal of the tip from the feed mechanisin, and a guide-member, of smallerA bore than theV rear end of the tip-structure and carried by said tip inposition back of that occupied by lthe rear end of a tip-carried lead-stick, said stem portion of the feed mechanism and bore of Isaid guide having relatively long, cylindrical cooperating guide surfaces adapted and arranged Apositively to align' the feed-mechanism stem with a tip-carried lead-stick before the forward endof said stem encounters the rear` end of said lead-stick. Y

9. In a pencil of the character described, the combination of a barrel, feed mechanism carried by the barrel and presenting a relavv i tively slender `stem portion ot said feed mechanism protruding-beyond the endof the barrel, ysaid feed mechanism having capacit.)v to receive a lead stick of predetermined length and including a lead-tube open at the Jiront end ol said stem portion; a tapered tip-member ot substantif-illy barreldiameter at its rear end and small diameter at its front end, said front end ot said tip being constructed for engagen'ient with` a lead-stick to carry the lead-stiel: therewith on ren'ioval olI the tip trom the teed mechanisim said tip beingdetachably connected with the barrel-carried mechanism; and an elongated guide member secured to said tip, said gnide, member and stem-portionhaving cooperating cylindrical guide-surfaces ot substantial longitudinal extent to insure accurate guidance oit the stem axially of the Iip, and said. guide-member ot the tip being arranged well in rear ot the position occupied by the rear end ot the tip-carried leadsticli to insure accurate alignn'ient of the lead-tube with the lead-stick betere said lead-tube can encounter the rear end of said lead-stick.

l0. In a pencil niechanisn' ot' the character described, the combination with. a barrel open at its end, otf a thimble shallowly seated in said barrel and vliXed therein, a fixed Slotted lead-tube carried by said thimble and extending'bevond the open end of the barrel and spaced apart Jfrom said thinible substantially to the rear end of the latter; a rotatable screw sleeve surroilnding said leadtube and at its rear end, adjacent the rear end 'ol the thiinble, heldl against longitudinal movementin or removal 'from the barrel and at its AForward end projecting well bevond the barrel and presenting a slender e \jflindrical guide surface surrounding and concentric with said lead-tube; a propeller member engaging said screw sleeve and having a portion entering the lead-tube to engage a lead-stiel; therein and therebyv determine the length otl lead-stick which said feed mechanisn'i may handle; a tip-structure tapering trom substantially barrel size at its rear end to a relatively small diameter at its torward end and at its forward end constructed tor engagement with the leadstick to carrythe latter with the tip on removal ot the tip from the feed mechanism; and a guide member carried by the tip adjacent the rear end ot the latter and having a relatively-slendcr guide cylinder arranged well in rear ot the position occupied by the rca-r end otthe tip-carried lead-stick, to cooperate with the guiding surface of said screw member and direct the lead-tube into positive alignment with the tip-carried leadstick. said slender cylindrical portion ot the guide entering the space between the screw sleeve -and the thimble when the parts are assen'ibled substantially as described.

GEORGE HOFMANN. 

